Last year, PSG also had a difficult start to the season, and if you remember, they played very poorly in the Champions League, and at one point there was a danger they wouldn't even make the top 24.
Their start was quite the same, 3 points from the first round, and they played much better in the Ligue, they were undefeated for 30 rounds not for 4 like now, then in CL they lost to Arsenal, now they face Barcelona, again Bayern like last season, so it could go even worse downhill this season.
I doubt they would be able to repeat the CL performance but the Ligue title is still safe.
Bookies have no issue with the last game, still 1.15 against Auxerre.
Yes, it's quite funny, but the Champions League winner got the toughest "group": Atalanta, Barcelona, Bayer, Bayern, Tottenham, Athletic, Sporting, Newcastle. If Atalanta and Bayer hadn't gone on sale, I would have called it a group of death. PSG have tough games and even now after their first win their chances of getting into the top 3 are estimated at 3.30, they are only 7th contenders, haha.
As for Ligue 1, they have it in their pocket. If I liked deposits, I'd place this bet at odds of 1.10.